The diabetic foot develops late into ulcers and necrosis of varying degrees on the distal toes and even the soles and backs of the feet. The differential diagnosis is as follows: 1. Ulcers occurring on the sole of the foot should be differentiated from diabetic neuropathic ulcers, when the arterial blood supply is not abnormal and the patient exhibits joint dislocation and plantar pressure ulcers with neuropathy. Patients show a loss of pain in the foot or even no sensation; 2. venous stasis ulcers of the lower extremities, mostly occurring above the medial ankle joint, with black legs but not black toes; 3. vasculitis, or thrombo-occlusive vasculitis, mostly in young men under 45 years of age, especially in the smoking population. Patients with diabetic foot first have diabetes to be able to be diagnosed with diabetic foot; while patients with atherosclerotic occlusive disease usually do not have diabetes, but can also develop gangrene or ulceration. In addition, wet gangrene occurs more often in diabetic feet, which manifests as infection, pus, ulceration, fluid flow, and even generalized fever with high white blood cell levels. Therefore symptoms are more frequent than in atherosclerotic occlusive disease and are treated differently than in simple atherosclerotic occlusive disease and vasculitis. If a patient has the above symptoms, he or she must go to a specialized vascular surgery department to see a vascular surgeon for diagnosis and treatment.